A dermal punch for extracting skin or tissue samples. The dermal punch has a blade having a pair of walls. Each wall is convex and opens towards each other. The walls are connected to each other at a pair of mating edges. Each wall has a cutting edge. In a preferred embodiment, the ratio of the minor axis to the major axis of the opening created by the walls is between 1 to 3 and 1 to 4, wherein the major axis extends through the mating edges. The cutting edge is formed of a plurality of teeth and the teeth have a sawtooth shape. The cutting edge has a projecting edge for each wall, and the projecting edge is concave. The cutting length is greater than twice the length of the projecting edge.
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11. A dermal punch comprising:
a handle having a vertical axis; and
a blade attached to the handle and having a first convex wall with a first plurality of teeth and a second convex wall with a second plurality of teeth, the first wall and the second wall forming a fusiform shaped cavity having a major axis and a minor axis shorter than the major axis such that the first plurality of teeth and the second plurality of teeth define a four corner cutting edge, each of the plurality of teeth extending in a distal direction that is parallel to the vertical axis;
the four corner cutting edge including the first wall having a first apex tooth and a first edge tooth and the second wall having a second apex tooth and a second edge tooth such that cuts move toward each other between an apex tooth and an adjacent edge tooth along the cutting edge during insertion into a region of skin of a patient.
1. A method of collecting tissue from a region of skin comprising the steps of:
holding a dermal punch having a cutting edge extending along a first wall with a first plurality of teeth and a second wall with a second plurality of teeth, the first wall and second wall meeting at mating edges to define a cavity having a fusiform shape, the cavity having a major axis and a minor axis that are perpendicular to a vertical axis of the dermal punch, each of the teeth extending in a distal direction that is parallel to the vertical axis of the dermal punch, at least one first apex tooth projecting at an apex of the first wall and at least one second apex tooth projecting at an apex of the second wall to define a plurality of apex teeth and at least one mating edge tooth projecting at each mating edge at which the first wall meets the second wall to define a plurality of edge teeth, the plurality of apex teeth and the plurality of edge teeth defining four corners of the cutting edge;
positioning the cutting edge relative to a selected region of skin of a patient;
initially puncturing the skin at all four corners of the cutting edge with the apex teeth and the mating edge teeth of the dermal punch by pushing the teeth along the vertical axis that is perpendicular relative to the region of skin; and
continuing to insert additional portions of the cutting edge into the skin of the patient to cut the selected region of skin.
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The present application claims the benefit and is a divisional of U.S. application Ser. No. 10/943,051 filed Sep. 16, 2004 and of U.S. Provisional Application No. 60/503,351, filed Sep. 16, 2003. The entire contents of the above applications are incorporated herein by reference.
Thousands of people are tested annually for melanoma, basal cell, squamous cell, and carcinogens, other abnormal skin growths (“moles”) and cancers, as well as bacterial or fungal skin infections. One of the most common tests of a skin lesion for diagnostic purposes is a dermal punch biopsy. This procedure entails the insertion of an instrument with a circular blade into the patient's skin and then subsequently rotating the instrument to cut out and remove the skin patch of interest. This provides tissue for microscopic analysis by a pathologist to obtain the correct diagnosis. This technique is nearly 100% effective, and accurate and is consequently widely used.
Although effective, this traditional punch biopsy usually leaves the wound open resulting in delayed healing and unsightly scars. The wound can result in scars that resemble “pock-marks” or “divets.” If the skin excision is large, the resultant wound can be closed by stitching but because of the circular shape of the wound, it can leave an ˜even skin edge.
The preferred embodiments of the invention relate to a dermal punch and a method of using it to extract tissue samples. In a preferred embodiment, the dermal punch has a handle portion and a blade having a pair of walls. The walls can have an external convex surface that are connected to each other at a pair of mating edges. Each wall has a distal cutting edge surrounding a cavity that defines the area of removal.
In a preferred embodiment, the ratio of the minor axis to the major axis of the opening or cavity defined by the walls is at least 1 to 2 and preferably between 1 to 3 and 1 to 4, wherein the major axis extends through the mating edges. As the size and shape of the lesion to be removed can vary, a variety of dermal punches of selected ratios and removal areas can be available depending on the anatomy and orientation of the specific site requiring biopsy, such as in a kit. The kit can include a single handle and a plurality of distal punch elements that can be mounted and detached from the handle as needed or individually mounted punches.
In a preferred embodiment, the cutting edge is formed of a plurality of teeth. The teeth can have a sawtooth shape, for example. In one embodiment, the distal tip of the teeth defines a projecting edge for each wall, and the projecting edge is convex or concave. The cutting length is greater than twice the length of the projecting edge for each wall.
In a preferred method, the cutting edge is positioned relative to a selected patch of skin. The skin is punctured by the cutting edge on the dermal punch by pushing the dermal punch into the skin. The dermal punch is removed from the body by pulling the dermal punch in a motion perpendicular to the skin. The dermal punch can also be tilted such that a portion of a cutting edge cuts laterally through the fat underlying the portion of skin being removed to aid in removal.
In one method, the positioning includes placing the apex of each projecting edge in contact with the skin, with the selected patch of skin to be excised interposed between each apex. The distal end is then manually inserted through the skin and rotated or rocked to sever the sample from the underlying layer. The wound in the skin is then closed. One method of closing is to use a medical glue or adhesive. Another method of closing uses a surgical staple. Another method uses surgical tape closure to pull the edges together.
In a preferred embodiment, the distal ends of the walls are tapered in towards the center axis of the handle. In another, the spacing between the walls or the angle of the taper is adjustable.
In one embodiment, the dermal punch includes a mechanism for closing the wound. The mechanism can be a device for applying a medical glue or adhesive. In another embodiment, the mechanism is a device for applying at least one staple or a suture.
Although effective, a traditional punch biopsy usually leaves the wound open, resulting in delayed healing and unsightly scars. The open wound results in scars that resemble “pock-marks.” If the skin excision is large, the resultant wound can be closed by stitching. The dermal punch according to the invention forms a wound with clean edges. A fusiform or spindle shape of an embodiment of the dermal punch with a distal taper can facilitate healing of the wound with minimal or no pocking on the skin.
The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of preferred embodiments of the invention, as illustrated in the accompanying drawings in which like reference characters refer to the same parts throughout the different views. The drawings are not necessarily to scale, emphasis instead being placed upon illustrating the principles of the invention.
Referring to the drawings in detail, where like numerals indicate like elements, a dermal punch is illustrated in accordance with a preferred embodiment of the present invention designated generally as 20.
Typically, the skin sample 38 is connected to the body by adhesion to the underlying fat layer. The skin patch 38 is removed from the body by a pair of forceps or a sharp object such as a needle.
The dermal punch 20 according to a preferred embodiment of the invention is shown in
As seen in
While the above refers to a pair of walls with a pair of mating edges, it is recognized that the walls can be formed by several methods including welding of two convex pieces or drawing an integral tube to the desired shape.
In this embodiment, the projecting edge 24 has a convex shape with a portion that extends the furthest distally, being spaced equidistant from the mating edges 28 and located the furthest from the longitudinal axis 50. This point on each wall 26 is defined as an apex 54.
The dermal punch 20 has a sawtooth or serrated edge 56 wherein each tooth 56 has a tip 58 positioned on the projection edge 24 and a root 60 interposed between each tooth 56 as best seen in
In a preferred embodiment, the knife edge has one surface shaped similar to a number 11 scalpel blade. The sawtooth shape with a knife edge extends between adjacent tips 58 and roots 60 therein allowing for an increased cutting length. In a preferred embodiment, the cutting length is greater than twice the length of the projecting edge 24. It is recognized that the projecting edge is a projection and not a physical edge and extends from tip to tip of the saw teeth. In one preferred embodiment, the cutting length is in a range of 2 to 4 times the length of the projection edge.
In addition, the cutting edge 22 of the dermal punch 20 is formed by the pair of walls that have an external convex surface and engage each other at the mating edges 28 as seen in
Referring to
In a preferred embodiment, the dermal punch 20 has 12 to 18 teeth per wall 26. Each tooth has a tip angle of β that in one embodiment is in a range of 15° to 35° and in a preferred embodiment is in a range of 22° to 28°. In addition, the root angle is γ and is in a range of 15° to 35° and in a preferred embodiment is in a range of 22° to 28°. Each of the two surfaces has a knife or cutting edge 62 as indicated above. In an embodiment, the knife edge 60 is shaped like a number 11 scalpel blade. In one embodiment, the knife edge is like a number 11 scalpel blade, with the knife edge, looking in cross section of the wall, extending from one surface to the other surface. In another embodiment, a pair of knife edge looking in cross section of the wall, each extend from the center line to another surface.
Referring to
The walls 26 define an opening 64 that has a fusiform or spindle shape. A major axis 70 of the opening 64 extends from one mating edge 28 to the other mating edge 28. A minor axis 72 extends from one wall 26 to the other wall 26 perpendicular to the major axis 70.
It is recognized that in certain embodiments that the distance between the tip 58 and the adjacent root 60 is greater than 1 millimeter, such as 1.5 millimeters in an embodiment for thick skin of the back or for “excision” of larger lesions mitigating the need for a scalpel excision.
The dermal punch 20 is positioned next to the skin so that the apex 54 of each of the walls is positioned so that the skin to be tested is positioned between the walls. The dermal punch 20 is pushed into the skin with a vertical and slightly rocking motion until the roots of all of the teeth have entered the skin (i.e. until the longitudinal axis 50 is in the same plane as the surface of the skin.)
The tips of the teeth engage and puncture the skin. As the dermal punch 20 is pushed into the skin, the cutting edge slices the skin (tissue) in a region of interest. The teeth provide a longer cutting surface and require less pressure to excise the sample. Therein, the dermal punch 20 is capable of producing a tissue sample with side walls or edges that are near perpendicular to the upper surface of the skin. The angle of sidewalls can vary slightly from a perpendicular orientation to facilitate bringing the skin edges together when closing the biopsy site. In that the dermal punch does not need to be rotated to cut the tissue sample, the fusiform-spindle-shape can be used.
The resulting wound from the dermal punch 20 has a smooth shape similar to the shape of a dermal punch as seen in
In the alternative, a dermal punch 90 is formed such that a pair of walls 26 are formed in a similar shape to that discussed above, however, the walls 26 are joined at a point 92 only at the mating edge 28 at the upper edge 86, i.e., the edge furthest from the cutting or blade edge 22, as seen in
Referring back to
When the dermal punch 100 of
In a preferred embodiment, the distance between the apex and the longitudinal axis, the location of the highest root, is 1 millimeter. The vertical position of the tips do not vary as greatly as the embodiment shown in
After the skin sample 38 from the area of interest is removed from the body, the wound may be closed using traditional “stitching.” Alternatively,
An alternative method of closing the wound is to staple or “clip” the wound.
An alternative embodiment of a dermal punch 150 is shown in
It is recognized that the dermal punch can have all the tips equally distant from the longitudinal axis, the longitudinal axis being defined as the location of the highest root. It is also recognized that the dermal punch can have all the roots of the teeth located on the longitudinal axis.
In accordance with a preferred embodiment, the dermal punch or a portion thereof is disposable and is formed of plastic and has a stainless steel cutting edge. It is recognized that the dermal punch can be formed of materials such as, for example, stainless steel or plastic, that are bio-compatible, can hold an edge and cut sharply.
Preferred embodiments of the present invention can include a kit having dermal punches of selected sizes and removal areas to accommodate the different sizes and shapes of lesions. The kit can include a single handle with a plurality of distal punch elements that can be mounted and detached as needed or a plurality of dermal punches of different sizes that are each packaged in separate sterilized packages for single use.
It is recognized that the dermal punch can, in an embodiment, have the convex walls with a smooth cutting edge without sawteeth or serrated edge.
The claims should not be read as limited to the described order or elements unless stated to that effect. Therefore, all embodiments that come within the scope and spirit of the following claims and equivalents thereto are claimed as the invention.
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